The Bird's-Eye View. 187 



sisting of fifteen separate pieces of bone, and strongly 

 resembling the eyeglass used by a working watch- 

 maker. 



The development of this focussing apparatus is 

 equally marked in birds that are in the habit of diving 

 in pursuit of fish. 



Watch the white gannet as he sails on long keen 

 wings over the restless sea. He has caught sight of a 

 fish. Pausing suddenly, he hovers like a hawk, though 

 his narrow, pointed tail seems ill adapted to steady 

 him in the air. Now falling swiftly perhaps a hundred 

 feet the gannet disappears in a cloud of spray. It 

 usually stays under but four or five seconds, but is 

 capable of much longer immersion, and indeed is 

 provided with space for the storage of air perhaps 

 for breathing purposes three times as great as that in 

 the human lungs. 



The better to follow its prey under water, the gannet 

 has very large eyes, and its sclerotic rings, composed 

 of twelve plates of bone, are especially broad and 

 thick. 



Those who have chased in vain the divers that in 

 summer are seen upon the Broads of Norfolk will 

 have had ample evidence of the keen vision of a 

 diving bird. 



It is on ' The Queen of the Broads ' perhaps that 

 the yachtsman, climbing out of his berth at daybreak, 

 sees the graceful figure of some large bird, very low in 

 the water, drifting along among the coots and moor- 



